Predicting the impacts of chemical pollutants on animal groups
Authors: Marcus Michelangeli, Jake M. Martin, Noa Pinter-Wollman, Christos C. Ioannou, Erin S. McCallum, Michael G. Bertram, Tomas Brodin
Journal: Trends in Ecology & Evolution (2022)

Wildlife are exposed to an increasing number and diversity of chemical pollutants.Chemical pollutants can elicit a range of sublethal effects on individual organisms, but research on how these contaminants affect social interactions and animal groups is severely lacking.It is imperative that perspectives from behavioural ecology and ecotoxicology are integrated, to increase our understanding of how contaminant effects on individuals might cascade to group-level processes.We present a conceptual framework for researchers and practitioners to guide the study of how chemical pollutants might affect the emergence, organisation, and function of animal social groups. Chemical pollution is among the fastest-growing agents of global change. Synthetic chemicals with diverse modes-of-action are being detected in the tissues of wildlife and pervade entire food webs. Although such pollutants can elicit a range of sublethal effects on individual organisms, research on how chemical pollutants affect animal groups is severely lacking. Here we synthesise research from two related, but largely segregated fields – ecotoxicology and behavioural ecology – to examine pathways by which chemical contaminants could disrupt processes that govern the emergence, self-organisation, and collective function of animal groups. Our review provides a roadmap for prioritising the study of chemical pollutants within the context of sociality and highlights important methodological advancements for future research. Chemical pollution is among the fastest-growing agents of global change. Synthetic chemicals with diverse modes-of-action are being detected in the tissues of wildlife and pervade entire food webs. Although such pollutants can elicit a range of sublethal effects on individual organisms, research on how chemical pollutants affect animal groups is severely lacking. Here we synthesise research from two related, but largely segregated fields – ecotoxicology and behavioural ecology – to examine pathways by which chemical contaminants could disrupt processes that govern the emergence, self-organisation, and collective function of animal groups. Our review provides a roadmap for prioritising the study of chemical pollutants within the context of sociality and highlights important methodological advancements for future research. Pollution arising from the production and consumption of synthetic chemicals now outpaces other environmental megatrends (e.g., rising CO2 emissions [1.Bernhardt E.S. et al.Synthetic chemicals as agents of global change.Front. Ecol. Environ. 2017; 15: 84-90Crossref Scopus (377) Google Scholar]). Increasing human reliance, coupled with world population growth and insufficient regulation, has driven an exponential rise in the number of chemical products marketed globally (>350 000 [2.Wang Z. et al.Toward a global understanding of chemical pollution: a first comprehensive analysis of national and regional chemical inventories.Environ. Sci. Technol. 2020; 54: 2575-2584Crossref PubMed Scopus (332) Google Scholar]), and a corresponding surge in chemical contaminants infiltrating the environment [3.Landrigan P.J. et al.Pollution and global health – an agenda for prevention.Environ. Health Perspect. 2018; 126084501Crossref PubMed Scopus (52) Google Scholar]. Ecosystems worldwide are now exposed to a staggering array of compounds from agrochemicals [4.Tang F.H.M. et al.Risk of pesticide pollution at the global scale.Nat. Geosci. 2021; 14: 206-210Crossref Scopus (293) Google Scholar] and metals [5.Briffa J. et al.Heavy metal pollution in the environment and their toxicological effects on humans.Heliyon. 2020; 6e04691Abstract Full Text Full Text PDF PubMed Scopus (1161) Google Scholar], to pharmaceuticals [6.Wilkinson J.L. et al.Pharmaceutical pollution of the world's rivers.Proc. Natl. Acad. Sci. U. S. A. 2022; 119e2113947119Crossref Scopus (328) Google Scholar] and personal care products [7.Dey S. et al.1 - Pharmaceuticals and personal care product (PPCP) contamination—a global discharge inventory.in: Prasad M.N.V. Pharmaceuticals and Personal Care Products: Waste Management and Treatment Technology. Butterworth-Heinemann, 2019: 1-26Crossref Scopus (84) Google Scholar]. Many pollutants degrade slowly and remain highly persistent in the environment, while others are released at a near-constant rate and are thus considered to be 'pseudo-persistent'. Consequently, chemical compounds have been detected in the tissues of a wide range of wildlife [8.Li Y. et al.Neonicotinoids and decline in bird biodiversity in the United States.Nat. Sustain. 2020; 3: 1027-1035Crossref Scopus (70) Google Scholar,9.Garcia-Cegarra A.M. et al.Persistence, bioaccumulation and vertical transfer of pollutants in long-finned pilot whales stranded in Chilean Patagonia.Sci. Total Environ. 2021; 770145259Crossref PubMed Scopus (8) Google Scholar], pervading entire food webs [10.Richmond E.K. et al.A diverse suite of pharmaceuticals contaminates stream and riparian food webs.Nat. Commun. 2018; 9: 1-9Crossref PubMed Scopus (165) Google Scholar,11.Yamamuro M. et al.Neonicotinoids disrupt aquatic food webs and decrease fishery yields.Science. 2019; 366: 620-623Crossref PubMed Scopus (145) Google Scholar]. A wealth of research dating back to Rachel Carson's seminal 1962 publication Silent Spring [12.Carson R. Silent Spring. Fawcett Publications, 1962Google Scholar] has documented the adverse impacts of chemical pollution on wildlife. Besides causing mortality at acutely lethal levels, chemical pollutants can elicit a range of sublethal effects on animals, even at minute concentrations – including disrupting their behaviour. Such effects may be hidden drivers of population declines and ecological instability [13.Saaristo M. et al.Direct and indirect effects of chemical contaminants on the behaviour, ecology and evolution of wildlife.Proc. R. Soc. B Biol. Sci. 2018; 28520181297PubMed Google Scholar], fuelling calls for better integration of behavioural indicators into the environmental risk assessment of chemicals [14.Ford A.T. et al.The role of behavioral ecotoxicology in environmental protection.Environ. Sci. Technol. 2021; 55: 5620-5628Crossref PubMed Scopus (83) Google Scholar]. However, nearly all research in behavioural ecotoxicology (see Glossary) is focused on behaviours of individual animals, with little consideration for how chemicals might affect social interactions and emergent group functions. This is a critical oversight because many animals engage in social interactions over their lifetime and live within highly structured societies or form loosely structured social groups (Figure 1). These animals coordinate their behaviours with conspecifics to provide protection against predation, gain reproductive opportunities, find food, and reduce energy expenditure [15.Krause J. et al.Living in Groups. Oxford University Press, 2002Google Scholar]. Collective behaviour thus directly affects both individual and group fitness. Here, we present a novel framework that outlines how chemical contaminants could disrupt behavioural processes that are instrumental in the emergence and self-organisation of animal groups. We formulate predictions for how these disruptions may ultimately affect collective outcomes, detail how social behaviours themselves may exacerbate or buffer the effects of contamination, and provide a roadmap for prioritising which pollutants and species to research. Importantly, our review presents a timely opportunity to integrate key perspectives in behavioural ecology and ecotoxicology – a critical step towards improving predictions on the environmental threat posed by chemical contaminants [1.Bernhardt E.S. et al.Synthetic chemicals as agents of global change.Front. Ecol. Environ. 2017; 15: 84-90Crossref Scopus (377) Google Scholar]. Chemical pollutants may influence collective behaviour by impacting the units that compose social groups (i.e., individuals) and/or the interactions among those units (i.e., sociality). Here, we detail how the effects of pollutants on individuals and their interactions can manifest across local and global spatial scales to change the formation and function of animal groups (Figure 2, Key figure ). Our framework integrates behavioural and social mechanisms that underlie the formation and function of different types of social systems, from highly dynamic fission–fusion societies to relatively stable social groups. To predict how contaminants might affect animal social groups, we first need to understand how they can influence individuals at environmentally realistic exposure levels. Documented impacts range from mortality to severe physiological and physical impairment, to subtler effects that may not elicit a stress or escape response. Here, we focus on examples of sublethal effects that could have cascading implications at the collective level (Box 1).Box 1Can we make generalised predictions for how certain chemical classes will impact animal groups?Chemical pollutants present a unique challenge due to the sheer number of different chemical classes, and the existence of numerous modes-of-action between and within these classes. The effects of chemicals can be species-specific, and contingent on several factors, including the degree of homology between non-target species and the intended target species. Further, many classes of chemical pollutants do not have a primary mode-of-action that is conventionally associated with behavioural disruption (e.g., antibiotics, antihistamines), or are not specifically designed to elicit behavioural effects (e.g., metals, surfactants), yet can still do so. This makes generating generalised predictions for many chemical classes difficult. However, for chemical classes with designed biological targets, and documented pathways for behavioural disruption, general predictions may be valuable for directing future studies on their impacts on animal groups and sociality. In Table I, we outline a series of general predictions for how individual-level effects induced by contaminants are expected to have corresponding group-level consequences, and we identify chemical classes that are predicted to induce these effects.Table IGeneral predictions for how individual-level effects induced by chemical pollutants could have corresponding group-level consequencesIndividual-level effectsChemical classesaFor each chemical class, we use an example chemical subgroup to narrow our predictions to specific biological targets. Chemical class and example chemical subgroup are 1–8.Group formationGroup dynamicsRefsAntisocial behaviour1,2,3,4,5Reduced tendency to accept and form social groups. Higher rejection rate from potential group members.Increased conflict amongst group members and weaker social networks. Altered social structure.[33.Whitlock S.E. et al.Environmentally relevant exposure to an antidepressant alters courtship behaviours in a songbird.Chemosphere. 2018; 211: 17-24Crossref PubMed Scopus (18) Google Scholar,34.Hubená P. et al.Prescribed aggression of fishes: pharmaceuticals modify aggression in environmentally relevant concentrations.Ecotoxicol. Environ. Saf. 2021; 227112944Crossref PubMed Scopus (8) Google Scholar,92.Santos M.E.S. et al.Traces of tramadol in water impact behaviour in a native European fish.Ecotoxicol. Environ. Saf. 2021; 212111999Crossref PubMed Scopus (9) Google Scholar, 93.Brodin T. et al.Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations.Science. 2013; 339: 814-815Crossref PubMed Scopus (602) Google Scholar, 94.Fenske L. et al.17-α-Ethinylestradiol modulates endocrine and behavioral responses to stress in zebrafish.Environ. Sci. Pollut. Res. Int. 2020; 27: 29341-29351Crossref PubMed Scopus (14) Google Scholar]Reduced anxiety and risk perception1,2,6Decrease in the propensity of individuals to join groups (particularly if grouping is primarily an antipredator strategy).Slow response times to group actions. Less group coordination and cohesion. Higher risk-taking and poorer predator evasion.[30.Cerveny D. et al.Bioconcentration and behavioral effects of four benzodiazepines and their environmentally relevant mixture in wild fish.Sci. Total Environ. 2020; 702134780Crossref PubMed Scopus (20) Google Scholar,57.Martin J.M. et al.The psychoactive pollutant fluoxetine compromises antipredator behaviour in fish.Environ. Pollut. 2017; 222: 592-599Crossref PubMed Scopus (90) Google Scholar,93.Brodin T. et al.Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations.Science. 2013; 339: 814-815Crossref PubMed Scopus (602) Google Scholar]Hyperactivity3,4Higher social interaction rates, but lower capacity to adjust behaviour for group formation.Faster group movement, altering group cohesion and polarisation. Hyperactive individuals may be rejected from unimpaired groups.[95.Horký P. et al.Methamphetamine pollution elicits addiction in wild fish.J. Exp. Biol. 2021; 224jeb242145Crossref PubMed Scopus (23) Google Scholar,96.De Serrano A.R. et al.Paternal exposure to a common pharmaceutical (Ritalin) has transgenerational effects on the behaviour of Trinidadian guppies.Sci. Rep. 2021; 11: 3985Crossref PubMed Scopus (6) Google Scholar]Lower activity/compromised locomotion1,5,6,7,8Inability for impaired individuals to join, or move between, groups.Slower group movement, altering group cohesion. Impaired individuals likely rejected from groups.[42.Eng M.L. et al.Imidacloprid and chlorpyrifos insecticides impair migratory ability in a seed-eating songbird.Sci. Rep. 2017; 7: 15176Crossref PubMed Scopus (105) Google Scholar,97.Ložek F. et al.Behaviour and cardiac response to stress in signal crayfish exposed to environmental concentrations of tramadol.Aquat. Toxicol. 2019; 213105217Crossref PubMed Scopus (17) Google Scholar, 98.Almeida C.H.S. et al.Sublethal agrochemical exposures can alter honey bees' and neotropical stingless bees' color preferences, respiration rates, and locomotory responses.Sci. Total Environ. 2021; 779146432Crossref PubMed Scopus (9) Google Scholar, 99.Bachour R.-L. et al.Behavioral effects of citalopram, tramadol, and binary mixture in zebrafish (Danio rerio) larvae.Chemosphere. 2020; 238124587Crossref PubMed Scopus (39) Google Scholar, 100.Matus G.N. et al.Behavior and histopathology as biomarkers for evaluation of the effects of paracetamol and propranolol in the neotropical fish species Phalloceros harpagos.Environ. Sci. Pollut. Res. Int. 2018; 25: 28601-28618Crossref PubMed Scopus (20) Google Scholar]Altered cognition4,7,8Reduced ability of impaired individuals to process social information including cues for group formation.Reduced social competence and inappropriate responses to social partners. Poorer group decision-making and coordination.[16.Bókony V. et al.Effects of two little-studied environmental pollutants on early development in anurans.Environ. Pollut. 2020; 260114078Crossref PubMed Scopus (15) Google Scholar,95.Horký P. et al.Methamphetamine pollution elicits addiction in wild fish.J. Exp. Biol. 2021; 224jeb242145Crossref PubMed Scopus (23) Google Scholar,101.Siviter H. et al.Quantifying the impact of pesticides on learning and memory in bees.J. Appl. Ecol. 2018; 55: 2812-2821Crossref PubMed Scopus (94) Google Scholar]Sensory disruption3,8Inability to attract and discriminate between potential group members. Reduced group assortment.Poor communication between group members. Uncoordinated groups and increased failure rate of collective actions.[20.Besson M. et al.Anthropogenic stressors impact fish sensory development and survival via thyroid disruption.Nat. Commun. 2020; 11: 1-10Crossref PubMed Scopus (26) Google Scholar,23.Ankley G.T. et al.Effects of the androgenic growth promoter 17-β-trenbolone on fecundity and reproductive endocrinology of the fathead minnow.Environ. Toxicol. Chem. 2003; 22: 1350-1360Crossref PubMed Google Scholar,60.Tomkins P. et al.An endocrine-disrupting agricultural contaminant impacts sequential female mate choice in fish.Environ. Pollut. 2018; 237: 103-110Crossref PubMed Scopus (28) Google Scholar]1-Antidepressants (e.g., selective serotonin reuptake inhibitors)2- Anxiolytics (e.g., benzodiazepines)3-Steroids (e.g., androgens)4- Psychostimulants (e.g., central nervous system stimulants)5- Analgesics (e.g., opioids)6- Beta-blockers (e.g., nonselective blockers)7- Anticonvulsants (e.g., dibenzazepines)8- Insecticides (e.g., neonicotinoids)a For each chemical class, we use an example chemical subgroup to narrow our predictions to specific biological targets. Chemical class and example chemical subgroup are 1–8. Open table in a new tab Chemical pollutants present a unique challenge due to the sheer number of different chemical classes, and the existence of numerous modes-of-action between and within these classes. The effects of chemicals can be species-specific, and contingent on several factors, including the degree of homology between non-target species and the intended target species. Further, many classes of chemical pollutants do not have a primary mode-of-action that is conventionally associated with behavioural disruption (e.g., antibiotics, antihistamines), or are not specifically designed to elicit behavioural effects (e.g., metals, surfactants), yet can still do so. This makes generating generalised predictions for many chemical classes difficult. However, for chemical classes with designed biological targets, and documented pathways for behavioural disruption, general predictions may be valuable for directing future studies on their impacts on animal groups and sociality. In Table I, we outline a series of general predictions for how individual-level effects induced by contaminants are expected to have corresponding group-level consequences, and we identify chemical classes that are predicted to induce these effects.Table IGeneral predictions for how individual-level effects induced by chemical pollutants could have corresponding group-level consequencesIndividual-level effectsChemical classesaFor each chemical class, we use an example chemical subgroup to narrow our predictions to specific biological targets. Chemical class and example chemical subgroup are 1–8.Group formationGroup dynamicsRefsAntisocial behaviour1,2,3,4,5Reduced tendency to accept and form social groups. Higher rejection rate from potential group members.Increased conflict amongst group members and weaker social networks. Altered social structure.[33.Whitlock S.E. et al.Environmentally relevant exposure to an antidepressant alters courtship behaviours in a songbird.Chemosphere. 2018; 211: 17-24Crossref PubMed Scopus (18) Google Scholar,34.Hubená P. et al.Prescribed aggression of fishes: pharmaceuticals modify aggression in environmentally relevant concentrations.Ecotoxicol. Environ. Saf. 2021; 227112944Crossref PubMed Scopus (8) Google Scholar,92.Santos M.E.S. et al.Traces of tramadol in water impact behaviour in a native European fish.Ecotoxicol. Environ. Saf. 2021; 212111999Crossref PubMed Scopus (9) Google Scholar, 93.Brodin T. et al.Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations.Science. 2013; 339: 814-815Crossref PubMed Scopus (602) Google Scholar, 94.Fenske L. et al.17-α-Ethinylestradiol modulates endocrine and behavioral responses to stress in zebrafish.Environ. Sci. Pollut. Res. Int. 2020; 27: 29341-29351Crossref PubMed Scopus (14) Google Scholar]Reduced anxiety and risk perception1,2,6Decrease in the propensity of individuals to join groups (particularly if grouping is primarily an antipredator strategy).Slow response times to group actions. Less group coordination and cohesion. Higher risk-taking and poorer predator evasion.[30.Cerveny D. et al.Bioconcentration and behavioral effects of four benzodiazepines and their environmentally relevant mixture in wild fish.Sci. Total Environ. 2020; 702134780Crossref PubMed Scopus (20) Google Scholar,57.Martin J.M. et al.The psychoactive pollutant fluoxetine compromises antipredator behaviour in fish.Environ. Pollut. 2017; 222: 592-599Crossref PubMed Scopus (90) Google Scholar,93.Brodin T. et al.Dilute concentrations of a psychiatric drug alter behavior of fish from natural populations.Science. 2013; 339: 814-815Crossref PubMed Scopus (602) Google Scholar]Hyperactivity3,4Higher social interaction rates, but lower capacity to adjust behaviour for group formation.Faster group movement, altering group cohesion and polarisation. Hyperactive individuals may be rejected from unimpaired groups.[95.Horký P. et al.Methamphetamine pollution elicits addiction in wild fish.J. Exp. Biol. 2021; 224jeb242145Crossref PubMed Scopus (23) Google Scholar,96.De Serrano A.R. et al.Paternal exposure to a common pharmaceutical (Ritalin) has transgenerational effects on the behaviour of Trinidadian guppies.Sci. Rep. 2021; 11: 3985Crossref PubMed Scopus (6) Google Scholar]Lower activity/compromised locomotion1,5,6,7,8Inability for impaired individuals to join, or move between, groups.Slower group movement, altering group cohesion. Impaired individuals likely rejected from groups.[42.Eng M.L. et al.Imidacloprid and chlorpyrifos insecticides impair migratory ability in a seed-eating songbird.Sci. Rep. 2017; 7: 15176Crossref PubMed Scopus (105) Google Scholar,97.Ložek F. et al.Behaviour and cardiac response to stress in signal crayfish exposed to environmental concentrations of tramadol.Aquat. Toxicol. 2019; 213105217Crossref PubMed Scopus (17) Google Scholar, 98.Almeida C.H.S. et al.Sublethal agrochemical exposures can alter honey bees' and neotropical stingless bees' color preferences, respiration rates, and locomotory responses.Sci. Total Environ. 2021; 779146432Crossref PubMed Scopus (9) Google Scholar, 99.Bachour R.-L. et al.Behavioral effects of citalopram, tramadol, and binary mixture in zebrafish (Danio rerio) larvae.Chemosphere. 2020; 238124587Crossref PubMed Scopus (39) Google Scholar, 100.Matus G.N. et al.Behavior and histopathology as biomarkers for evaluation of the effects of paracetamol and propranolol in the neotropical fish species Phalloceros harpagos.Environ. Sci. Pollut. Res. Int. 2018; 25: 28601-28618Crossref PubMed Scopus (20) Google Scholar]Altered cognition4,7,8Reduced ability of impaired individuals to process social information including cues for group formation.Reduced social competence and inappropriate responses to social partners. Poorer group decision-making and coordination.[16.Bókony V. et al.Effects of two little-studied environmental pollutants on early development in anurans.Environ. Pollut. 2020; 260114078Crossref PubMed Scopus (15) Google Scholar,95.Horký P. et al.Methamphetamine pollution elicits addiction in wild fish.J. Exp. Biol. 2021; 224jeb242145Crossref PubMed Scopus (23) Google Scholar,101.Siviter H. et al.Quantifying the impact of pesticides on learning and memory in bees.J. Appl. Ecol. 2018; 55: 2812-2821Crossref PubMed Scopus (94) Google Scholar]Sensory disruption3,8Inability to attract and discriminate between potential group members. Reduced group assortment.Poor communication between group members. Uncoordinated groups and increased failure rate of collective actions.[20.Besson M. et al.Anthropogenic stressors impact fish sensory development and survival via thyroid disruption.Nat. Commun. 2020; 11: 1-10Crossref PubMed Scopus (26) Google Scholar,23.Ankley G.T. et al.Effects of the androgenic growth promoter 17-β-trenbolone on fecundity and reproductive endocrinology of the fathead minnow.Environ. Toxicol. Chem. 2003; 22: 1350-1360Crossref PubMed Google Scholar,60.Tomkins P. et al.An endocrine-disrupting agricultural contaminant impacts sequential female mate choice in fish.Environ. Pollut. 2018; 237: 103-110Crossref PubMed Scopus (28) Google Scholar]1-Antidepressants (e.g., selective serotonin reuptake inhibitors)2- Anxiolytics (e.g., benzodiazepines)3-Steroids (e.g., androgens)4- Psychostimulants (e.g., central nervous system stimulants)5- Analgesics (e.g., opioids)6- Beta-blockers (e.g., nonselective blockers)7- Anticonvulsants (e.g., dibenzazepines)8- Insecticides (e.g., neonicotinoids)a For each chemical class, we use an example chemical subgroup to narrow our predictions to specific biological targets. Chemical class and example chemical subgroup are 1–8. Open table in a new tab 1-Antidepressants (e.g., selective serotonin reuptake inhibitors) 2- Anxiolytics (e.g., benzodiazepines) 3-Steroids (e.g., androgens) 4- Psychostimulants (e.g., central nervous system stimulants) 5- Analgesics (e.g., opioids) 6- Beta-blockers (e.g., nonselective blockers) 7- Anticonvulsants (e.g., dibenzazepines) 8- Insecticides (e.g., neonicotinoids) Exposure to chemical pollutants can lead to dramatic morphological alterations, including changes to body size [16.Bókony V. et al.Effects of two little-studied environmental pollutants on early development in anurans.Environ. Pollut. 2020; 260114078Crossref PubMed Scopus (15) Google Scholar], colouration [17.Chatelain M. et al.Do trace metals influence visual signals? Effects of trace metals on iridescent and melanic feather colouration in the feral pigeon.Oikos. 2017; 126: 1542-1553Crossref Scopus (14) Google Scholar], and sex [18.Kidd K.A. et al.Collapse of a fish population after exposure to a synthetic estrogen.Proc. Natl. Acad. Sci. 2007; 104: 8897-8901Crossref PubMed Scopus (1577) Google Scholar]. Perhaps most fundamental to animal social behaviour, pollutants can directly interfere with sensory anatomy involved in social communication (e.g., visual, auditory, olfactory, and tactile senses). Various compounds from surfactants to metals, pesticides, and herbicides can damage chemoreceptors and olfactory function in fish [19.Razmara P. et al.Mechanism of copper nanoparticle toxicity in rainbow trout olfactory mucosa.Environ. Pollut. 2021; 284117141Crossref PubMed Scopus (13) Google Scholar,20.Besson M. et al.Anthropogenic stressors impact fish sensory development and survival via thyroid disruption.Nat. Commun. 2020; 11: 1-10Crossref PubMed Scopus (26) Google Scholar], amphibians [21.Sievers M. et al.Contaminant mixtures interact to impair predator-avoidance behaviours and survival in a larval amphibian.Ecotoxicol. Environ. Saf. 2018; 161: 482-488Crossref PubMed Scopus (44) Google Scholar], and insects [22.Williamson S.M. Wright G.A. Exposure to multiple cholinergic pesticides impairs olfactory learning and memory in honeybees.J. Exp. Biol. 2013; 216: 1799-1807PubMed Google Scholar], greatly reducing their ability to detect cues. In extreme cases, chemical exposure can even lead to the development of new sensory anatomy. For instance, female fathead minnows, Pimephales promelas, exposed to 17β-trenbolone developed nuptial tubercles, which are communication structures typically only found in males [23.Ankley G.T. et al.Effects of the androgenic growth promoter 17-β-trenbolone on fecundity and reproductive endocrinology of the fathead minnow.Environ. Toxicol. Chem. 2003; 22: 1350-1360Crossref PubMed Google Scholar]. Beyond morphological abnormalities, exposure to chemical pollutants often causes physiological, neurological, and hormonal disruption, leading to changes in phenotypic expression [24.Goodchild C.G. et al.Male zebra finches exposed to lead (Pb) during development have reduced volume of song nuclei, altered sexual traits, and received less attention from females as adults.Ecotoxicol. Environ. Saf. 2021; 210111850Crossref PubMed Scopus (9) Google Scholar, 25.Yamindago A. et al.Fluoxetine in the environment may interfere with the neurotransmission or endocrine systems of aquatic animals.Ecotoxicol. Environ. Saf. 2021; 227112931Crossref PubMed Scopus (10) Google Scholar, 26.Straub L. et al.Negative effects of neonicotinoids on male honeybee survival, behaviour and physiology in the field.J. Appl. Ecol. 2021; 58: 2515-2528Crossref Scopus (9) Google Scholar]. For instance, pollutants can alter an individual's metabolic state, leading to increased foraging and activity [27.Tan H. et al.Chronic exposure to a pervasive pharmaceutical pollutant erodes among-individual phenotypic variation in a fish.Environ. Pollut. 2020; 263114450Crossref Scopus (23) Google Scholar]. Changes to neurological and cognitive function can occur when contaminants mimic or block the actions of neurotransmitters, neurohormones, or steroid hormones that modulate animal behaviour [28.Vaudin P. et al.When pharmaceutical drugs become environmental pollutants: potential neural effects and underlying mechanisms.Environ. Res. 2021; 205112495PubMed Google Scholar]. Chemical exposure can also disrupt neurological function by impacting the expression of key receptors for signalling molecules, the functionality of enzymes, or the modulation of neural transmission via de- or hyperpolarisation [29.Richardson J.R. et al.Neurotoxicity of pesticides.Acta Neuropathol. 2019; 138: 343-362Crossref PubMed Scopus (211) Google Scholar]. Pollutants stemming from human pharmaceutical medications, for instance, can alter wildlife behaviours, such as activity [30.Cerveny D. et al.Bioconcentration and behavioral effects of four benzodiazepines and their environmentally relevant mixture in wild fish.Sci. Total Environ. 2020; 702134780Crossref PubMed Scopus (20) Google Scholar,31.Buřič M. et al.Environmentally relevant concentrations of tramadol and citalopram alter behaviour of an aquatic invertebrate.Aquat. Toxicol. 2018; 200: 226-232Crossref PubMed Scopus (50) Google Scholar], risk-taking [30.Cerveny D. et al.Bioconcentration and behavioral effects of four benzodiazepines and their environmentally relevant mixture in wild fish.Sci. Total Environ. 2020; 702134780Crossref PubMed Scopus (20) Google Scholar,32.Chabenat A. et al.Alteration of predatory behaviour and gro